Sensation of tight band around ankle

Have had CFS for 24 years and this is the first time i have had this symptom. Don't know if it is related to CFS or something else. Has anyone experienced this. Also, leg feels somewhat weak when walking.

After year 25 of CFS I had a similiar experience. Eventually mine started to swell and the my foot and groing area started to turn black. Found out that it was a blood clot in the saphenous vein - a few days in the hospital and the infections went away. The clot has cleared but they say the walls are very thick and will remain that way. So I watch it and take precautions - such as no tight socks etc.